The present invention relates to an apparatus for the vaporization of elemental sulfur by means of carrier gas, and especially to an apparatus which has a thermally insulated vessel for the melting of elemental sulfur, provided with heating devices, a stirrer, and a feed pipe for elemental sulfur, and at least one other vessel, provided with heating devices, a stirrer, a feeding member for carrier gas and an outlet pipe for sulfur vapors, and possibly also provided with thermal insulation, for the vaporization, by means of carrier gas, of the molten elemental sulfur emerging from the former vessel.
Conventional vaporizers usually operate at a high temperature and pressure (pressure vessel) in relation to the vaporization point of the substance to be vaporized. The most simple industrially used vaporizer is a boiler heated by means of electricity fuel gas vapor, in which the temperature of the liquid to be vaporized is raised to the boiling point or above it (pressure vessel). Owing to the small heat transfer area the vaporization efficiency of the apparatus is relatively low. Further, when a high temperature gradient is used, a vapor film inhibiting the transfer of heat is easily formed.
Most industrially used vaporizers are various types of pipe, cell or lamella vaporizers in which the heat transfer area has been increased by the implementation of various structures. The liquid to be vaporized can be either inside or outside the pipes.
In the apparatus for the production of sulfur vapor according to U.S. Pat. No. 2,582,794, molten sulfur at the boiling point is pumped into a separate vaporizer heated by means of fuel gases, and sulfur is heated in this vaporizer in a bundle of pipes.
The production of elemental sulfur vapor by means of carrier gas is a commonly used vaporization method in connection with phase-equilibrium determinations performed at a controlled partial pressure of sulfur. In the apparatuses according to U.S. Pat. Nos. 2,595,447 and 2,637,630, preheated air or oxygen is introduced into molten sulfur in order to burn the sulfur, forming sulfur dioxide, whereby elemental vapor is vaporized from the molten sulfur. The above-mentioned prior known apparatuses for the vaporization of elemental sulfur have relatively high purchase price and operating costs. Pressure vessels are known to be expensive, and thermal losses from several separate containers can be relatively high in spite of good thermal insulation. The space requirement of these prior known apparatuses is also relatively large.
The object of the present invention is thus to provide an apparatus which is simpler and more economical in terms of energy than the previous apparatuses for the vaporization of elemental sulfur by means of carrier gas; an apparatus by means of which it is possible to produce elemental sulfur vapor of a high partial pressure for various sulfidization processes to be carried out in solid or molten state.